Generally, electronic devices include input units for inputting data and output units for outputting data. Key button units can be generally classified as input units, and display units including liquid crystal display (LCD) modules can be generally classified as output units.
Recently, touch screen devices have been released, which can input or output data at the same location to notably reduce volumes of electronic devices and to diversify functions thereof. In the case of such touch screen devices, a transparent panel is disposed on a top of an LCD module, thereby inputting or outputting at the same time. Touch panels can be classified into various types of touch panel such as resistive touch panels, electrostatic capacitive touch panels, ultrasonic touch panels, infrared (IR) sensitive touch panels, electromagnetic touch panels and the like.
Generally, in the case of touch screen devices, data is inputted by using a finger of a user. However, recently, multiple touch screen devices have been released, in which an input device having a pen shape, generally designated as a touch pen, is provided as an auxiliary input element and data is selectively inputted by using the touch pen. Also, individual sensing elements are provided in addition to touch panels of touch screen devices in such a way that data input using a pen input device and data input using a touch panel are separately used.
As described above, electromagnetic induction methods are generally used when using touch pens. That is, electronic devices respectively include a pen touch panel that is generally designated as a digitizer, in which a plurality of coils are disposed to be orthogonal to one another, as an additional sensing element separately from a touch panel, and touch pens respectively include a resonance circuit. Accordingly, an alternating current (AC) signal is applied to coils of a pen touch panel to be operated, when a touch pen accesses or is place in proximity to a touch screen of such electronic device, a coil of the pen touch panel, adjacent to the touch pen forms a magnetic field, a resonance frequency occurs in the touch pen while being resonant with the magnetic field, and the generated resonance frequency is sensed by a control unit of the electronic device, thereby recognizing a corresponding touch position.